EP-4735348-A1 - POLYESTER STRAPS USEFUL IN BINDING APPLICATIONS AND USES THEREOF

EP4735348A1EP 4735348 A1EP4735348 A1EP 4735348A1EP-4735348-A1

Abstract

The present invention relates to polyester straps, methods of their manufacture, systems and uses thereof, particularly as may be used in binding applications of discrete articles into bundles. The polyester straps comprise voids extending into the interior of the strap from one or more of the surfaces thereof.

Inventors

D'OTTAVIO, John
GRAHAM, RYAN
MISCHISSIN, Michael

Assignees

EAM-Mosca Corporation

Dates

Publication Date: 20260506
Application Date: 20240827

Claims (9)

1. A plastic strap formed of an at least partially crystalline thermoplastic material which is ultrasonically welded, the plastic strap having a length, a width and a thickness, two substantially parallel major faces having a width and a length separated by the thickness, at least one of the major faces having a plurality of voids extending into the thickness from the major face, each of the voids having straight boundary lines at their periphery wherein they intersect a major face of the plastic strap, each of the voids present in the interior of the plastic strap and having a depth, a void surface area and a void volume measurable from the major face of the plastic strap, wherein per unit length of the plastic strap the cumulative void surface area is from 20% to 90%, preferably from 30%> to 50%, and the cumulative void volume is from 5% to 65%, preferably from 10% to 60%, especially preferably from 25% to 30%, in the region of the plastic strap which is subsequently ultrasonically welded and at least partially melted forming a bond therebetween.
2. The plastic strap of claim 1, wherein the plastic strap comprises a substantial portion of a polyalkylene terephthalate.
3. The plastic strap of claim 2, wherein the polyalkylene terephthalate is polyethylene terephthalate.
4. The plastic strap of any of preceding claim which has a width not in excess of 5 mm.
5. The plastic strap of any preceding claim wherein the voids are present in an array.
6. The plastic strap of any preceding claim wherein the voids have boundary lines of parallelogram shape having four apices and which voids have a pyramidal cross-section.
7. The plastic strap of any preceding claim wherein peripheral boundary of most of the voids present on a major face of a plastic strap are entirely within the width of the plastic strap, but which include incomplete voids having peripheral boundaries which intersect the and edge of the plastic strap.
8. A process for tensile bundling of loads which comprises the steps of; utilizing a plastic strap according to any preceding claim, forming a loop about the load with the plastic strap, and, ultrasonically welding parts of the looped plastic strap.
9. A bundled load comprising an ultrasonically welded formed loop of a plastic strap according to any of claims 1-7.

Description

POLYESTER STRAPS USEFUL IN BINDING APPLICATIONS, METHODS OF MANUFACTURE, SYSTEMS AND SES THEREOF This application claims priority to US Provisional patent application serial no. 63/580077, filed 01. Sep.2023, and by this reference thereto incorporates its entire disclosure herein. The present invention relates to polyester straps, methods of their manufacture, systems and uses thereof, particularly as may be used in bundling applications of discrete articles into bundles. Plastic straps (or “straps”, as well as “strapping”) formed primarily of synthetic polymers are widely used in known-art apparatus which provide tensile bundling of loads, particularly bundling of discrete article into bundles. Primarily such polymers are based on polyolefins or polyesters. Such discrete articles bundled with such plastic straps include, without limitation, generally planar, generally two-dimensional articles such as sheet like articles as well as folded articles such as cardboard boxes, as well as three-dimensional articles, including without limitation, packaged articles, boxes, cartons, and the like. Prior to bundling the articles are typically stacked or layered in register to provide an assembly which is then formed into a bundle utilizing one or more straps which are first drawn around the assembly to form a continuous loop, then the strap is tensioned and thereafter the loop is sealed or otherwise bonded or affixed to retain the tension within the strap of the continuous loop. One common technique includes bonding overlapping parts of the strap to form a loop, such as by heating. Bundles may include one or more such tensioned loops in order to retain the bundled articles within the assembly. However many such apparatus and straps used in bundling do exhibit various technical problems and shortcomings. Some of these have been addressed previously, and the prior art includes documents which address strapping devices and straps themselves which provide certain benefits. The following are a non-limiting list of such documents: US Patent 8859682, US Patent 9315700; US Patent 10669085; US Published Application 2011/0319565A1, US Published Application 2019/0255761 Al, US Published Application 2019/0270231 Al, WO 2015/042631 Al, WO 2015/042632A2, and EP3052690A1. JP 2005-001679 discloses a thermoplastic synthetic band useful in a packaging machine, the thermoplastic necessarily used is limited to a polyolefin and in particular polypropylene which is not a crystalline or semi-crystalline polymer which may be oriented on a microscopic scale. US Patent No. 10669085 discloses a tape-like packaging element which may be formed of a polyester. The tape-like packaging element is limited to having cavities having no angles or apicies, and are preferably elliptical or circular as is depicted in its drawing figures. Friction welding is taught as the means for bonding faces of the tape-like packaging element. With attention to Fig. IB, the depth of these elliptical cavities appears to be shallow relative to the entire thickness of the strap, with the embossment depth being between 50 and 300 microns, but preferably 150 microns. However no other dimensions relating to the depth of the tape-like packaging element is described in the specification and only the disclosure of the cross-section of Fig. lb provides an indication that the tape-like packaging element is substantially thicker than any embossment depth. Further, at column 2, line 51 through column 3, line 3 this document highlights deficiencies in non-circular or non-elliptical cavities, viz., cavities having straight boundary lines which are cited to exhibit a detrimental propensity of undesired tearing of the tape-like packaging element. Although straps and strapping devices of the prior art may provide certain benefits, there remains a real and continuing need in the art to provide further solutions and advantages in this technical field, particularly wherein narrower width straps are contemplated. One shortcoming in the relevant art relates to overcoming technical challenges relating to the use of polyester strapping. Such polyester strapping is primarily offered in widths ranging from about 9 mm and higher, and while narrower polyester strapping is known, such do not typically have widths less than 6 mm. This is due to both manufacturing challenges as well as the ability to produce a satisfactory weld joint relative to the material’s tensile strength. Using both heat seal and friction welding machines on polyester strapping, particularly low width (i.e., not exceeding about 9 mm) crystallizes the molecular chains creating an unstable brittle weld joint. The heat produced also emits toxic vapors when welding polyester. In low load applications requiring strapping having widths in the 5mm-6mm range, polypropylene (“PP”) is therefore the primary polymer used. However, there are superior benefits specific to polyester in these applications such as polymer sustainability, low